JPS61141787A - Control of oven temperature in coke oven - Google Patents

Abstract

PURPOSE:To surely detect a tendency toward increase or decrease of oven temp. and to prevent failure of carbonization, by controlling the oven temp. by using a value estimated on the part data when deviation between a set value and a measured value exceeds a predetermined value. CONSTITUTION:The output of a temp. sensor 10 provided at the top of the combustion chamber of a coke oven is subjected to digital conversion by an A/D converter 11 and averaged by an interval leveler 12, and then inputted to an oven temp. setting means 13b and a data buffer 14. When deviation between a set value and a measured value of the oven temp. exceeds a predetermined limit, a gas flow rate is decided by a gas fraction amt. calculator 17 using a forecast oven temp. in future estimated by using data of the past oven temp. by switching a switch 16, to control a gas flow controller 18. When said deviation is below the limit, the gas flow rate is calculated by using a practically measured oven temp. and the coke oven temp. is controlled by controlling the gas flow controller 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a furnace temperature control method when performing combustion control of a system such as a coke oven that has a large heat capacity and a large thermal response delay.

[Conventional technology]

Generally, the cross section of a coke oven is shown in Figure 3.
There is a heat storage chamber 3 in the lower part of the furnace body, and the combustion chamber (flue) 1 and carbonization chamber 2 are arranged alternately in the upper part.

In recent coke oven combustion control, the above combustion chamber (flue)
Furnace temperature control has been introduced in which a temperature sensor is installed at the top of the coke oven to control the furnace temperature to a constant temperature according to the operating rate of the coke oven. The control system flow that implements this is outlined in Section 4.
Such furnace temperature control shown in the figure is based on the temperature deviation (
The gas flow rate control is performed by calculating the gas flow rate ΔV to be changed from ΔT).

Conventionally, this control method has good controllability when the temperature deviation (ΔT) is relatively small, but when the temperature deviation (ΔT) is large, such as when the coke oven operating rate is changed or the operation is stopped, Due to a delay in the thermal response of a coke oven, a time delay before the so-called fuel control action is reflected in the furnace temperature measurement, changing the gas flow rate becomes an overaction, causing hunting in the furnace temperature and resulting poor carbonization. For example, an example of changing the furnace temperature during shutdown is shown in FIG.

The combustion chamber of a coke oven differs depending on the furnace type, such as a two-part type or a hairpin type, but normally each flue burns every 20 minutes, as shown in Figure 6, which shows an example of a two-part furnace. Switch the combustion side gas flow 8. The combustion method is such that the exhaust side gas flow 9 is repeated alternately.

In automatic furnace temperature control, when the combustion switching is 20 minutes, one cycle is usually taken into account for 40 minutes (combustion + exhaust), and the average value during this period by the temperature sensor is used as the furnace temperature measurement value (T
pma). That is, measurements obtained every 40 minutes (
The gas flow rate is changed according to the deviation ΔT between the set value (Tpma) and the set value (Tsma), but in this method, if the temperature deviation ΔT increases due to disturbances such as coke oven shutdown or production reduction, the above-mentioned It was causing problems.

[Problem that the invention seeks to solve]

Therefore, instead of always changing the gas flow rate by setting V = f (ΔT), when ΔT exceeds a certain limit value, that is, when 1ΔT1≧x 'O, the thermal response delay (θ) is taken into consideration. A control method is required.

The present invention focuses on such problems and automatically adjusts the furnace temperature by predicting the furnace temperature after 0 hours from the past furnace temperature trend when IΔT1≧X″C, and using this predicted furnace temperature value as a control parameter. The purpose of this invention is to provide a control method and improve the above-mentioned problems.

[Means for solving problems]

In order to solve the above problems, the present invention analyzed actual data and developed an effective and simple method as a result.

The present invention provides a coke oven furnace temperature control method that compares a measured furnace temperature of a coke oven combustion chamber with a preset furnace temperature set value, and controls the furnace temperature based on the deviation to match the furnace temperature set value. If the deviation between the furnace temperature set value and the measured value is greater than a predetermined limit value, control is performed using an estimated furnace temperature value that predicts the furnace temperature in the future using past furnace temperature measurement data. , a coke oven furnace temperature control method is characterized in that when the temperature is less than a limit value, control is performed using an actually measured furnace temperature value.

The method of the present invention focuses on the fact that the thermal response delay of a coke oven is 3 to 4 hours, and that oven temperature fluctuations are gradual and can be approximated to a quadratic function for about 10 hours. The temperature data is used to predict the furnace temperature after 3 to 4 hours, and feed-forward control is performed based on this predicted value. This method can prevent furnace temperature hunting caused by delayed thermal response and the resulting poor carbonization. FIG. 7 shows the predicted value of the furnace temperature when the quadratic function was predicted using the method according to the present invention.As can be seen, the predicted value and the actual measured value correspond well, and it can be said that control using the predicted value is possible.

The method for obtaining this predicted value is as follows. Figure 8 (a
), the interval average data of the furnace temperature for each time interval τ (40 minutes), that is, the measured value of the furnace temperature (Tp), is set as D (N).

... (1) At current time 1=0, past furnace temperature data D(1), D
(, 2), . . . have been obtained, and from these, the furnace temperature 0 hours after the current time is estimated by quadratic function approximation. Here, θ=about 3 to 4 hours. Let this estimated value be L.

The method for obtaining the estimated value is shown below.

As shown in FIG. 8(b), when estimating ru(O), that is, the value from t=0 to t=τ, past data, D (
1) Using , D (2) and D (3), applying it to a quadratic function and extrapolating it, '6(0) can be found by the following formula.

-tj(0) =3I)(1) -30(2)+D (3)...(2
) D(N) = ao +al XN+a2 XN2...
(2a) Here, ao, a5, and a2 are coefficients.

That is, D (1), D (2), D (3)
When applied to a quadratic function that satisfies this, that is, equation (2a), D (1) −ao + a 1 + a2D (2)
= a 6 + a I X 2 + a 2 X
22D (3)=&6 +aIX3+a2 X3”...
・It can be expressed as (3).

Here, ``[3 (0) is equal to ao, therefore, by solving equation (3) only for ao, we can obtain the saving (0). This is (
2) is the formula.

Similarly, in order to obtain the estimated value r after 0 hours, depending on the level of θ to be obtained, as shown in Fig. 8 (C),
Past data D(1).

D(2),... using 3 data every n pieces,
It is sufficient to calculate presence=ao by performing a calculation similar to the formula (2). Note that the prediction calculation is performed each time data is updated every hour.

In the present invention, the temperature deviation ΔT is 1ΔT due to disturbances such as idle operation.
When 1≧x℃, grasp the tendency of the furnace temperature to rise or fall based on the furnace temperature prediction value (To) obtained as above,
Automatically control.

Note that x is usually about 5 to 10°C.

When 1ΔTl<x''c, feedback control similar to the conventional one is performed, and the switching is performed by the changeover switch 16 in FIG. 1 by determining the temperature deviation ΔT.

〔Example〕

FIG. 1 shows an apparatus configuration for carrying out the present invention, and FIG. 2 shows a flowchart thereof. In FIG. 11, and is averaged by an interval averaging device 12 during the time interval τ due to combustion switching, and is output as a furnace temperature measurement value (Toma) every hour.

13 is a furnace temperature setting and comparator, and 14 is a data/comparator.
15 is an arithmetic unit. The furnace temperature measurement value is input into the setting device 13b and the data buffer 14 every hour. The data buffer 14 always stores about 20 pieces of data in memory and is updated every hour, but by inputting every 3 pieces of this data to the arithmetic unit,
A predicted furnace temperature value is calculated.

17 is a gas action amount calculator, which calculates the gas flow rate to be changed from the temperature deviation ΔT.

Further, 16 is a changeover switch, and temperature deviation 1ΔTl≧x
Switch in sequence under the condition of '0 (x = 5 to 10°C). Due to this.

When 1ΔT1≧x”O, control based on predicted values is achieved.

In other words, (a) When 1ΔT1≧x”c, the switch 16 connects the gas action amount calculator 17 and the gas in the route of the interval averaging device 12 → data eight-folder 14 → furnace temperature prediction calculator 15 → deviation calculator 13a. Controls the flow rate controller 18.

(b) (If Δ71<x'o, the interval averaging device 12
→Using the path of the deviation calculator 13b, normal control as shown in FIG. 2 is performed.

〔Effect of the invention〕

The present invention predicts the furnace temperature using an estimated value based on past data when the deviation between the set value and the measured value of the furnace temperature exceeds a predetermined limit value, and controls the furnace temperature based on this prediction. Therefore, compared to conventional methods, it is superior in that it can accurately grasp trends in the rise and fall of furnace temperature, and prevents overheating due to delayed thermal response during changes in coke oven operating conditions such as shutdown. This makes it possible to prevent poor carbonization and excessive injection of fuel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the device configuration of an embodiment of the present invention;
FIG. 2 is a flowchart of an embodiment of the method of the present invention, FIG. 3 is a cross-sectional view of the furnace body of a coke oven, FIG. 4 is a system flow diagram of combustion control, and FIG. 5 is a graph showing an example of furnace temperature fluctuation due to disturbance. Figure 6 is a schematic diagram of the flow of combustion gas in a coke oven, Figure 7
The figure is a correlation diagram of measured furnace temperature values and predicted values, and FIG. 8 is a graph showing a furnace temperature prediction method. l... Combustion chamber 2... Carbonization chamber 3... Regenerator chamber 4... Temperature sensor 5... Gas flow rate controller 6... Flue draft controller 7... Coke oven
8... Combustion side gas flow 9... Exhaust side gas flow
lO...Temperature sensor 11...A/D converter 12...Section averaging device 13...Furnace temperature setting, comparator 14...Data buffer 15...Furnace temperature prediction calculator 16... ...Selector switch 17...Gas action amount calculator 18...Gas flow rate controller

Claims (1)

[Claims] 1. A coke oven furnace temperature control method that compares a measured furnace temperature of a coke oven combustion chamber with a preset furnace temperature set value, and controls the furnace temperature to match the furnace temperature set value based on the deviation, If the deviation between the furnace temperature set value and the measured value is equal to or greater than a predetermined limit value, control is performed using an estimated furnace temperature value that predicts the furnace temperature at a future time using past furnace temperature measurement data, A coke oven furnace temperature control method, characterized in that when the temperature is less than a limit value, control is performed using an actually measured furnace temperature value.